Anti-&#34;Chimney&#34; Effect Jacket

ABSTRACT

A jacket that protects against heat and fire, comprising a heat-shrink strip that shrinks when heated to a given temperature, and which is arranged so as to achieve a tightening of the jacket around the body of its wearer due to shrinking of the strip at the said temperature.

This present invention relates generally to garments for protection against heat and fire, in particular to garments worn by firefighters. Specifically, it concerns a protective jacket equipped with a strip that shrinks under the effect of heat.

Garments that protect against heat and fire must satisfy a certain number of criteria, in particular:

protection against radiant heat and against convective heat,

good thermal stability of the component materials,

non-inflammability and

good impermeability.

At the present time, in order to create firefighting jackets, use is made of multi-layer structures that are generally composed of four layers, namely:

-   -   an outer fabric;     -   a waterproof perspiration layer, generally combined with a         substrate;     -   a thermal barrier;     -   a final lining.

The multi-layer structure can also be composed of three layers, with the waterproof perspiration layer being laminated directly behind the outer fabric:

-   -   a laminated outer fabric;     -   a thermal barrier;     -   a final lining.

The internal layer acting as a thermal barrier is generally composed of a spun felt that is capable of trapping air. The thermal insulation created by this trapped air provides considerable protection against the flow of heat.

Firefighting working clothes are generally composed of an over-trouser and a protective jacket. More rarely, it takes the form of a one-piece combination but, in this case, comfort is reduced due to the lack of openings in the garment.

It has been observed that the working clothes of firefighters that include a jacket constitute a particular risk. Under the effect of exposure to flame, a heat convection phenomenon takes place, consisting of a rising of the hot air and of the flames under the jacket or between the layers of the jacket, if the lining is not attached to the outer fabric. This can lead to serious burns on the back and even up to neck of the wearer of the garment. This heat convection effect is also known in other thermal applications, in particular the ventilation of buildings, and called the “chimney effect”. In the case of the garments employed for protection against heat and fire, the applicant was able to demonstrate this effect by means of tests on a thermal model.

The wearing of a tightened firefighter's belt outside of the protective jacket results in the elimination, or at least the reduction to a significant degree, of the air passages that can give rise to this chimney effect.

The firefighter's belt is an integral part of the firefighters' apparel. In France, its use was made obligatory by the order dated 6 May 2000, establishing the clothing to be worn by firefighters. The work-belt is used by the firefighters both as a support for equipment (glove carrier, lamp carrier) and to anchor themselves to an automatic or semi-automatic pivoting ladder. It should be noted that, in practice, the work-belt must not be too tight in order to allow the circulation of a certain flow of air in the jacket. In fact, the air trapped in the protective jacket, at the internal layer acting as a thermal barrier, plays a part in the protection of the firefighter. An excessively tight work-belt prevents the natural circulation of the air under the jacket and inside the jacket and has the effect firstly of reducing the protective quality of the working jacket, and secondly of reducing the comfort to the wearer of the said jacket, due to this lack of ventilation. The custom is therefore to close the work-belt around the waist to as to allow this circulation of air.

As a result, when the firefighters are combatting a fire, there exists a potential risk that the chimney effect will occur, unless a suitable solution can be found to this problem.

This present invention is designed to overcome this drawback, by proposing a protective jacket, in particular for firefighters, which allows the circulation of air under and inside the jacket in normal times and which prevents the chimney effect when fighting a fire.

Thus, the invention concerns a jacket that protects against heat and fire, characterised by a strip that shrinks at a given temperature T and that is arranged so as to achieve a tightening of the jacket around the body of its wearer due to the shrinking of the strip at the said temperature T.

By “strip” is meant here an elongated element which can consist of either a part that is attached to or built into the jacket, or a coating applied onto the jacket.

The said strip that shrinks under the effect of the heat can in particular take the form of of a ribbon of fabric, preferably placed inside the said jacket, such as on an inner surface of the said jacket. It can be incorporated into the material constituting the final lining in the form of groups of threads, such as weft threads for example. The said strip can also take the form of a strip of shrinkable material coating the inside of the protective jacket.

By the “inside” of the protective jacket is meant here the surface that is facing the skin, and the “inner surface” of the protective jacket here refers to the reverse side of this garment.

The shrinkable strip is preferably located on the part of the jacket covering the hips, that is where the diameter of the body is largest and therefore where the jacket is closest to the body.

When fighting a fire, when the temperature surrounding the wearer reaches the threshold determined for the temperature T where the shrinking of the heat-shrink strip occurs, the flow of air at such a temperature, endeavouring to penetrate under the jacket, will give rise to this shrinking effect, and therefore the tightening of the garment around the body, thus preventing the passage of this hot air and preventing the phenomenon of heat convection toward the top of the garment, as in the chimney effect.

The heat-shrink strip is preferably made from a non-inflammable material. It must also have a good mechanical resistance to heat, in order to retain good integrity even at very high temperature, and be able to perform its primary function, which is to keep the protective jacket closed tightly against the body of the wearer during fire intervention.

It has been found that in order to meet the requirements of the invention, a strip designed to be fitted to a protective jacket in particular must shrink by at least 15% at a temperature of at least 250° C.

According to a second aspect, the invention concerns a strip intended in particular to be fitted to a jacket that protects against heat and fire, characterised in that it shrinks under the effect of heat by at least 15% at a temperature of at least 250° C.

The invention has the advantage that it will be understood more clearly in the light of the single FIGURE, which represents, in schematic manner, a front view of a protective jacket, with a shrinkable strip, according to one implementation variant of the invention.

The shrinkable strip 1 is attached by stitching to the inner surface 2 of the protective jacket 3 at the level of the hips. It is therefore located below the line 4 marking the waist of the person. In fact, it has been observed that, in this position, it has maximum protective effect against the rise of hot air and flames.

As mentioned above, the existence of a layer of air between the protective jacket and the garments worn under it (shirt, tee-shirt or polo-neck shirt), and the ability of air to circulate between these garments and the exterior, as well as the existence of a layer of air on the inside of the jacket, at the level of the thermal barrier, are particularly important, as they play a part in the protection of firefighters when combatting fire. They are also an important factor in the comfort of the wearer, cooling the body and removing perspiration.

A jacket fitted with the shrinkable strip 1 has the benefit of natural circulation of air in a normal situation. When the thermal risk arises, that is when the circulating air reaches a given temperature T, the strip 1 reacts in a predictable manner and prevents any chimney effect that could be created. In fact, when a person who is wearing the jacket described is subjected to extreme conditions of heat and fire, then the said jacket tightens onto his body, due to shrinking of the said shrinkable strip, and this tightening completely prevents the passage of air that could lead to the creation of the chimney effect.

In the example illustrated, the protective working jacket 3 for firefighters is of slightly waisted shape, with sleeves that facilitate the amplitude of any movement, while still preserving covering of the trouser. It has a frontal closure 5 provided by a flap system and rapid opening, and with no opening to the back.

In the first implementation variant of the invention which is shown in the FIGURE, the shrinkable strip 1 is fixed to the inner surface 2 of the protective jacket 3. In this case, according to a particular method of implementation, the shrinkable strip 1 is attached to the final lining constituting the innermost layer of the protective jacket 3. This can be achieved:

by stitching the ribbon of heat-shrink fabric continuously on the said final lining,

by coating the said final lining with a strip of heat-shrink material,

by integrating into the manufacture of the final lining a group of heat-shrink threads, acting as a strip according to the invention, such as weft threads for example.

In another method of implementation, which is not illustrated, of this first variant, the shrinkable strip 1 is slid through loops which are fixed onto the inner surface 2 of the protective jacket 3. The number of loops must be sufficient so that the said strip 1 is retained in a more or less continuous manner. It should be designed to suit the size of the jacket, providing one loop every ten centimeters for example.

In the above case, the shrinkable strip 1 is attached to the final lining of the protective jacket 3 and can be fitted to an existing protective jacket, by the application of a few modifications.

An additional advantage can be seen from the fact that the heat-shrink strip is attached to the final lining. When shrinking leads to tightening of the garment, there is some movement of the lining in relation to the other constituents of the garment, creating a layer of air inside the garment and locally increasing its insulating properties.

In a second implementation variant of the invention, the shrinkable strip 1 is fixed internally in the multi-layer structure employed in the constitution of the protective jacket 3.

When the heat-shrink strip is composed of a textile component, the choice of the nature of the threads or fibres used in the constitution of the said part, and the weave of the latter, is determine according to the position of the strip 1 in the multi-layer structure. It is preferable to choose a type of thread or fiber that shrinks at a sufficiently high temperature when the strip is fixed externally to the inner surface of the lining of the protective jacket 3 (first variant), and a type of thread or fiber that shrinks at a lower temperature, when the strip 1 is fixed internally in the said multi-layer structure (second variant).

Among the non-inflammable materials that shrink under the effect of the heat and having good mechanical resistance to heat, appropriate to constitute the shrinkable strip 1, use can be made of the polymers of meta-aramid type. One can mention by way of an example the polymer marketed by the Kermel company under the title of Kermel Tech, which has fibres of polyamides-imide, or pure T84 polyimid fibres, which have the characteristic of shrinking at temperatures of about 280-300° C. In this case, the shrinkable strip 1 can be woven, knitted or braided from threads or fibres of the said meta-aramid type polymers.

In the second implementation variant of the strip 1, use can be made of materials that shrink at lower temperatures, such as polyester. 

1.-13. (canceled)
 14. A jacket that protects against heat and fire, comprising a strip that shrinks when heated to a given temperature, the strip being arranged so as to achieve the tightening of a jacket around the body of a wearer due to shrinking of the strip at said given temperature.
 15. A jacket according to claim 14, wherein the shrinkable strip is positioned at a part of a jacket covering the strip.
 16. A jacket according to claim 14, wherein the strip is made from a non-flammable material.
 17. A jacket according to claim 14, wherein the strip is fixed to an inner surface of the jacket.
 18. A jacket according to claim 14 and having a multi-layer structure, wherein the strip is fixed internally in the said multi-layer structure.
 19. A jacket according to claim 18 and having a multi-layer structure that includes at least three layers, wherein an innermost layer is a final lining, and wherein the strip is attached to the final lining.
 20. A jacket according to claim 19, wherein the strip is stitched onto or incorporated into said final lining.
 21. A jacket according to claim 19, wherein the strip is coated onto said final lining.
 22. A jacket according to claim 17, wherein the strip is threaded through loops fixed onto the said inner surface.
 23. A jacket according to claim 17, wherein the strip includes polymers of a meta-aramid type.
 24. A jacket according to claim 18, wherein the strip includes a material of a polyester type.
 25. A strip designed to equip the protective jacket of claim 14, wherein the strip shrinks under an effect of heat by at least 15% at a temperature of at least 260° C.
 26. A strip according to claim 25, which is woven, knitted or braided from threads or fibers of polymer of a meta-aramid type. 